The Effects of Hydrolytic Enzyme Treatments on Three British Columbian Interior Fir Kraft Pulps Differing in Their Initial Fiber Coarseness

Abstract

The effects of carbohydrate-degrading enzymes on three softwood kraft pulps, differing primarily in their initial fiber coarseness, were assessed. The pulps were treated with three different enzyme preparations (a crude cellulase, an endoglucanase, and a xylanase) to assess the potential of the different enzymes to alter handsheet properties and to evaluate their effects on fiber coarseness. All enzymatic treatments increased handsheet densities irrespective of the furnish used. The most significant modifications in handsheet properties were evident after treatment with either the crude cellulase or the endoglucanase. Although increased densification occurred with all the pulps, the degree of fiber coarseness of the original pulp influenced the magnitude of response to the different enzymatic treatments. While the tensile index of the coarser pulp was improved by treatment with the crude cellulase, a similar trend was not evident with the pulps of lower coarseness. In contrast, the tensile strength of all pulps, irrespective of the inherent fiber coarseness, was improved by the endoglucanase treatments. The tear strength decreased after treatments with both the crude cellulase and endoglucanase. Xylanase treatments did not significantly alter the handsheet properties of any of the pulps, regardless of the nature of the starting furnish.